BP封堵漏油暫獲成功 生態影響待長期監測

The "static kill" procedure begun yesterday to prepare for sealing BP's blown-out well in the Gulf of Mexico has been successful, according to the company and National Incident Commander retired Coast Guard Admiral Thad Allen.

For the static kill, engineers pumped drilling mud from vessels on the surface down the well's riser pipe and through the capping stack, a complex set of valves atop the wellhead that has kept oil from spilling into the gulf since it was put in place July 15.

Now engineers will decide whether or not to put cement down the well, a decision that Admiral Allen said depends on what conditions they believe exist inside the damaged drill pipe a mile below the surface.

The next step will be to finish off the relief well that will finally kill the troublesome leaking well.

Most of the oil from the BP spill in the Gulf of Mexico has either evaporated or been burned, skimmed, recovered from the wellhead or dispersed, according to a scientific report released today by the federal government.

An Oil Budget Calculator developed by the National Oceanic and Atmospheric Administration, NOAA, and the Department of the Interior enabled 25 government and independent scientists to provide measurements and best estimates of what happened to the spilled oil.

The report was produced by scientific experts from several federal agencies, with peer review of the calculations by both other federal and non-federal scientists.

NOAA Administrator Jane Lubchenco told reporters today, "We can account for all but about 26 percent. And of that, much of that is in the process of being degraded and cleaned up on the shore."

"This analysis uses the recently released calculation of 4.9 million barrels, plus or minus 10 percent, and includes both direct measurements as well as the best estimates where direct measurements were not possible," Lubchenco said.

The figure of 4.9 million barrels is the government's Flow Rate Technical Group estimate from Monday. Of that, 800,000 barrels were collected by BP in ships for trasport to refineries on shore, leaving an estimated 4.1 barrels of oil that entered gulf waters.

The new report estimates that a third of the total amount of oil released in the Deepwater Horizon/BP spill was captured or mitigated by the Unified Command recovery operations, including burning, skimming, chemical dispersion and direct recovery from the wellhead.

An additional 25 percent of the total oil naturally evaporated or dissolved, and 16 percent was dispersed naturally into microscopic droplets.

The residual amount, about 26 percent, is either on or just below the surface as residue and weathered tarballs, has washed ashore or been collected from the shore, or is buried in sand and sediments, the report finds.

Dispersed and residual oil remain in the ecosystem until they degrade through natural processes.

The federal report does not make conclusions about the long-term impacts of oil. Fully understanding the damages and impacts of the spill on the Gulf of Mexico ecosystem will take time and continued monitoring and research.

Lubchenco said, "A large number of research vessels continue to be active in the gulf, and they're underway to understand the concentrations of subsurface oil and the rate at which it is being biodegraded."